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  • Journal of the American College of Cardiology Vol. 59, No. 18, 2012 2012 by the American College of Cardiology Foundation ISSN 0735-1097/$36.00

    Cardiac Imaging

    Usefulness of Fluorine-18 Positron Emission Tomography/Computed Tomography for Identification ofCardiovascular Implantable Electronic Device Infections

    Jean-Franois Sarrazin, MD,* Franois Philippon, MD,* Michel Tessier, MD, Jean Guimond, MD,Franck Molin, MD,* Jean Champagne, MD,* Isabelle Nault, MD,* Louis Blier, MD,* Maxime Nadeau,*Lyne Charbonneau, RN,* Mikal Trottier, MD, Gilles OHara, MD*

    Quebec City, Quebec, Canada

    Objectives This study evaluated the usefulness of fluorodesoxyglucose marked by fluorine-18 (18F-FDG) positron emissiontomography (PET) and computed tomography (CT) in patients with suspected cardiovascular implantable elec-tronic device (CIED) infection.

    Background CIED infection is sometimes challenging to diagnose. Because extraction is associated with significant morbidi-ty/mortality, new imaging modalities to confirm the infection and its dissemination would be of clinical value.

    Methods Three groups were compared. In Group A, 42 patients with suspected CIED infection underwent 18F-FDG PET/CT.Positive PET/CT was defined as abnormal uptake along cardiac devices. Group B included 12 patients withoutinfection who underwent PET/CT 4 to 8 weeks post-implant. Group C included 12 patients implanted for 6months without infection who underwent PET/CT for another indication. Semi-quantitative ratio (SQR) was ob-tained from the ratio between maximal uptake and lung parenchyma uptake.

    Results In Group A, 32 of 42 patients with suspected CIED infection had positive PET/CT. Twenty-four patients with posi-tive PET/CT underwent extraction with excellent correlation. In 7 patients with positive PET/CT, 6 were treatedas superficial infection with clinical resolution. One patient with positive PET/CT but negative leukocyte scan wasconsidered false positive due to Dacron pouch. Ten patients with negative-PET/CT were treated with antibioticsand none has relapsed at 12.9 1.9 months. In Group B, patients had mild uptake seen at the level of the con-nector. There was no abnormal uptake in Group C patients. Median SQR was significantly higher in Group A(A 2.02 vs. B 1.08 vs. C 0.57; p 0.001).

    Conclusions PET/CT is useful in differentiating between CIED infection and recent post-implant changes. It may guide appro-priate therapy. (J Am Coll Cardiol 2012;59:161625) 2012 by the American College of CardiologyFoundation

    Published by Elsevier Inc. doi:10.1016/j.jacc.2011.11.059

    Cardiovascular implantable electronic device (CIED) infec-tion is one of the most feared complications of deviceimplantation. The incidence of CIED infections is 1.9 casesby 1,000 implants/year (1,2). The total number of CIEDinfections is increasing, mainly with new clinical indicationsand the growing number of implants worldwide (3). Defin-itive CIED infection diagnosis is often challenging. Inaddition, CIED infection treatment can be invasive, requir-

    From the *Department of Medicine, Division of Cardiology, Institut universitaire decardiologie et pneumologie de Qubec, Qubec City, Quebec, Canada; and theDepartment of Medical Imaging, Division of Nuclear Medicine, Institut universi-taire de cardiologie et pneumologie de Qubec, Qubec City, Quebec, Canada. Allauthors have reported that they have no relationships relevant to the contents to thispaper to disclose.

    Manuscript received July 7, 2011; revised manuscript received November 9, 2011,accepted November 22, 2011.

    ing complete extraction of the generator and all leads. Leadextraction is associated with significant morbidity (majorcomplications 1.5% to 2%) and mortality (0.8%) (4,5).New imaging modalities to confirm the infectious processand its dissemination would be of clinical value.

    See page 1626

    Combined fluorodesoxyglucose marked by fluorine-18(18F-FDG) positron emission tomography (PET) and com-puted tomography (CT) is a well-established imaging mo-dality that allows 3-D measurement of metabolic activitywithin an organ obtained from the emission of positronsfollowing disintegration of an injected radioactive product.The value of 18F-FDG PET/CT is already recognized in

    oncology for cancer diagnosis and staging, and in cardiology

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    1617JACC Vol. 59, No. 18, 2012 Sarrazin et al.May 1, 2012:161625 PET/CT and Device Infection

    to assess myocardial viability. 18F-FDG PET/CT is alsosed for infection detection associated with vascular orrthopedic prostheses (69). There are few case reports1013) and only 2 small pilot studies (14,15) in theiterature where 18F-FDG PET/CT has been used forIED infection diagnosis. 18F-FDG PET/CT appears as

    an interesting adjunct for CIED infection diagnosis because itallows the use of 18F-FDG as a marker. This is a glucosenalogue, which is incorporated and retained within the cellsith higher metabolic activity. It might help the clinician to

    onfirm the diagnosis of CIED infection, determine theystemic extension of the infectious process, and justify annvasive procedure.

    The goal of this study was first to evaluate the usefulnessf 18F-FDG PET/CT for the detection of CIED infec-ions. Secondly, because there is sometimes a real clinicalhallenge to diagnose a CIED infection or superficial skinnfection or inflammation in recent post-implant patients,e tested a group of patients with recent implants and no

    linical suspicion of infection to assess their baseline18F-FDG uptake level.

    Methods

    The protocol was approved by the Ethics Committee fromthe Institut universitaire de cardiologie et pneumologie deQuebec.

    Three groups of consecutive patients were prospectivelycompared. The first group (Group A suspected CIEDinfection) included patients with clinically suspected CIEDinfections (n 42). CIED infection was defined by thepresence of 1 of the following (5,16): 1) pocket infection local signs of inflammation at the generator pocket, includ-ing erythema, warmth, fluctuance, wound dehiscence, ten-derness, or purulent drainage (n 26); 2) device erosion cutaneous erosion with percutaneous exposure of the gen-erator and/or leads (n 6); 3) lead endocarditis massadherent to a lead in a patient with positive blood culturesor other suggestive features for infection or lead tip cultures(n 7); and 4) persistent or recurrent bacteremia in theabsence of another identifiable source (n 3).

    Treatment decisions were on the basis of the degree ofcertainty of the CIED infection diagnosis, results of con-ventional tests, and clinical guidelines (5). Results of the18F-FDG PET/CT were transmitted to the treating phy-sicians, but the exam was only complementary and neverused alone for the final decision on the management of thesepatients. Extraction was performed when deep CIED in-fection (i.e., infection involving the generator and/or theleads) was suspected. The second group (Group B controls: acute phase) included patients with recent deviceimplantation but without signs of infection in order to knowthe background residual inflammation at 4 to 8 weekspost-implant (n 12), the period where the diagnosiscan be more challenging. These patients were recruited at

    the time of their first follow-up visit approximately 1

    month post-implant. Finally, thethird group (Group C con-trols: chronic phase) includedpatients with remote device im-plantation (6 months) with-

    ut signs of infection who un-erwent 18F-FDG PET/CT

    for another indication (n 12).Clinical data were collected

    rom all patients, including bloodork (white blood cell count,eutrophils count, C-reactiverotein level, and blood culturesf available). A clinical correla-ion was performed in patientsho had a transesophageal echo-

    ardiogram (TEE) and/or ex-raction in addition to 18F-FDGET/CT.

    18F-FDG PET/CT. All patients underwent 18F-FDGPET/CT (GE Discovery PET/CT, GE Healthcare, Pisca-taway, New Jersey) after an 8-h fasting period. PET imagingwas performed 65 17 min after injection of 8.1 1.8 mCi of

    DG (equivalent to 293.1 74.4 MBq). Simultaneously, aow-dose CT without intravenous contrast but with gastricpacification was obtained for attenuation correction andnatomic localization. The capillary glucose was measuredt the time of the injection. Limited imaging to the torsond superior abdomen was performed in Group B to limitadiation exposure.

    Each case was reviewed by 2 experienced nuclear physi-ians. Discordant analyses were resolved by consensus. Thenalysis was performed using MIMvista software (MIMoftware Inc., Cleveland, Ohio). Both attenuation-orrected as well as nonattenuation-corrected images wereeviewed in order to recognize artifacts related to theorrection of attenuation in proximity of an object of highensity (e.g., metal of generator), but only the nonttenuation-corrected images were used for final interpreta-ion. A positive 18F-FDG PET/CT was defined as an

    abnormal 18F-FDG uptake near the generator pocketand/or along the CIED (i.e., generator or leads). Sites ofabnormal 18F-FDG uptakes were noted as well as the site ofmaximal 18F-FDG uptakes. Sites of abnormal 18F-FDGptakes were separated by areas: skin (superficial), subcuta-eous tissue, surrounding of generator, overlying leads, and

    ntravascular/intracardiac. A qualitative visual score wasoted: none (score 0), mild hypermetabolism (equal or

    ess to lung parenchyma; score 1), moderate hypermetab-lism (more intense than lung parenchyma; score 2), and

    severe hypermetabolism (very intense uptake; score 3).There was interobserver agreement for the qualitative visualscore as well as for the final PET/CT conclusion on whetheror not CIED infection was present.

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